Stents or stent grafts are forms of transluminal prosthetic components which are used to maintain, open or dilate stenotic lesions in body lumens or to cover and repair an aneurysm. It is often the case that an aneurysm occurs at a branch or bifurcation in a vessel. To repair such an aneurysm using modular components, one current technique is to initially deploy across the aneurysm a main body stent or stent graft having a side wall opening. The side wall opening is aligned with the side branch ostium. A second stent or stent graft is then deployed through the main body stent side wall opening and into the side branch vessel. This modular repair approach requires the modular components to be effectively sealed at their connection points to prevent blood leakage into the aneurysm. In addition the modular components must be locked or joined together to prevent subsequent relative displacement of the modular components. Similar requirements apply to those procedures that use multiple stent grafts that are coupled together to increase the effective length of the repair device.